Zeratul's journey has brought him back to Aiur and the rotting carcass of the Overmind. With it, Zeratul hopes to establish a mental link with the Zerg entity to uncover more details of what fate is in store for the universe.

Defense

Your first order of business is to start fortifying your base with turrets to thwart incoming Zerg attacks. There will be a timer in the upper right of the screen the clocks down to when the next attack will occur, so get to building up your defensive line. All the while you should be building more Probes to harvest Minerals at an accelerated rate.

Once you have established your defenses, it's time to start building up your forces. Build a number of Gateways and upgrade them to be Warp Gates. Start building Stalkers to help support the Colossus's and move your forces East to take control of the abandoned Warp Gate -- this is where you want to establish your second base.

Obelisk Locations

There are two Obelisks located on this map. One is located near the Abandoned Warp Gate to the East of your starting base and the other is to the North from your starting base. Power these up by building a Pylon near them. Make sure you interact with both of these before Zeratul interacts with the final zone so you get credit for the Research.

Escort Zeratul

Once the second base has been established you'll be able to grow your forces expeditiously. While the main objective is to have Zeratul interact with each of the highlighted zones with the Overmind, you need to clear out all of the Zerg that surround these areas -- Zeratul must survive.

The best way to make this happen is to have a large group of units walk through these lightly defended Zerg bases. Once all of these defenses have been removed, bring in Zeratul to interact with each zone until you have completed the mission.